1. Field of the Invention
The present invention relates to emery wheel grinding machine with an adjustable chuck, and more particularly, to an emery wheel grinding machine equipped with an adjustable drill bit chuck suitable for shaving the drill bit or a cutter of a two or more faced and variously lengthed blade of a hobbing cutter other than a single blade one.
2. Description of the Related Art
A conventional portable grinding machine, as it was disclosed and published by Taiwan Pat. No. 286610, 155338, is composed of a housing, a cap covered at one end thereof, a transmission gearing equipped in the housing, a emery wheel and guiding members. When it is to be used, the whole unit is set on an electric motor with the grinding machine coupled with the main shaft of the electrical drill so as to impart the rotational power of the electrical drill to the emery wheel with transmission gearing for running. At the same time, a drill bit or cutter to be shaved is affixed to the machine unit with the guiding members so as to shave and grind the drill bit or cutter blade to a desired extent.
With the grinding machine described above, the grinding or shaving effect can only reach to the very small part surrounding the central pointed drill head without reaching further to the portion of the blade edge at the recessed clearance, that greatly degrades the effect of finishing drill bit.
For an improvement, the applicator invented an innovative Portable Drill Bit Grinding Machine which was patented by Taiwan Pat. No. 547228. As shown in FIG. 1, this newly developed apparatus is essentially composed of an emery wheel 20 driven by a power source associated with a work fixture and a drill bit fixing means 30 for operation. The work fixture is cooperated with a first grinding base 40 for the purpose of affixing the blade of the drill bit in such a manner that its clearance angle is closely fitted to the tilted grinding surface 21 of the emery wheel 20. Then, the work fixture is cooperated with a second grinding base 50 for the purpose of affixing the blade of the drill bit in such a manner that its spiral angle to be closely fitted to the tilted grinding surface 21 of the emery wheel 20.
As shown in FIG. 1, the drill bit fixing means 30 comprises a work fixture fastening base 31 for setting the work fixture, and a drill bit fastening jig 32. The work fixture fastening base 31 is provided with a mounting hole that allows the work fixture to be engaged in, and a rotation limiting post with a prescribed angle provided at the circumference of the mounting hole.
The first grinding base 40 is engaged to a machine housing 10 in front of the emery wheel 20 aligned in the same center line, and is kept a distance with the emery wheel 20 equal to that between the work fixture fastening base 31 and the drill bit fastening jig 32. The first grinding base 40 is approximately configured in L shape with an arcuate sliding slot 41 formed at the base surface thereof. By fastening the arcuate sliding slot 41 with a bolt 42, the first grinding base 40 can practically keep a relevant angle with the emery wheel 20 so as to grind and shave a variety of drills such as standard drill, rugged drill, or ebonite drill having the blades of different clearance angles and recesses.
The first grinding base 40 has a vertical wall 46 on which being provided with a mounting hole 43 for engaging the work fixture therein, and two rotation limiting posts 44, 45 with a prescribed angle and distance are formed at the circumference of the mounting hole 43. The mounting hole 43 is upwardly inclined with an angle about 10˜25° in order to fit the direction of the blade of the drill bit to be shaved.
The second grinding base 50 is engaged to the machine housing 10 with a bolt 51 above the emery wheel 20 keeping a distance with the latter equal to that between the work fixture fastening base 31 and the drill bit fastening jig 32. The second grinding base 50 has a mounting hole 52 for engaging the work fixture therein and a rotation limiting post 53 with a prescribed angle standing on the circumference of the mounting hole 52.
However, the improved portable grinding machine patented by No. 547,228 described above is still having a limited use for grinding conventional drill or cutter only, it is inapplicable to a particular drill or cutter with two or more blades.
For these defects noticeable on the prior art, further improvement is seriously required. The inventor has dedicated great efforts for years to studying and improving these defects and came up with the present invention to be disclosed herein.